CN1090847C

CN1090847C - Method and apparatus for increasing receiver immunity to interference

Info

Publication number: CN1090847C
Application number: CN95197662A
Authority: CN
Inventors: 查尔斯·E·惠特利; 保罗·E·彼特泽尔; 理查德·K·科恩费尔德; 安娜·L·韦兰
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 1994-12-16
Filing date: 1995-12-11
Publication date: 2002-09-11
Anticipated expiration: 2015-12-11
Also published as: AU717794B2; MY117285A; TW301826B; ES2268553T3; IL116364A0; EP1503517B1; FI117840B; CN100459452C; EP1513268B1; CN1638304A; CA2467295A1; RU2448411C2; DE69533405D1; FI118662B; ATE339811T1; CA2467276C; CN1396721A; HK1004453A1; RU2305363C2; CN1211948C

Abstract

The method and apparatus of the present invention improve the immunity to interference of a radio receiver. The power level of a received signal is detected. If the power level meets or exceeds a predetermined power threshold, the low noise amplifier (703) is by-passed, thus increasing the intercept point of the receiver components. Alternative embodiments include the use of an RF power detector (105) to control the front-end gain (110) as a function of jammer power. In lieu of a switchable RF gain block (730), several methods of continuous gain control are proposed. Continuous gain control allows the interference suppression and sensitivity of the receiver to be adjusted at lower signal levels than the switchable gain block. A method of the present invention adjusts the input gain by a predetermined amount.

Description

Improve the method and apparatus of noise immunity of receiver

Technical field

The present invention relates to radio communication.The invention particularly relates to improvement to the wireless communication receiver immunity to interference.

Background technology

There is multiple cellular radio telephone system using at present.These systems comprise that " Advanced Mobile Phone System " (AMPS) and two kinds of digital honeycomb communication systems: time division multiple access (TDMA) and code division multiple access (CDMA).The enforcement of digital honeycomb communication system has solved the capacity problem that AMPS runs into.

All cellular radio telephone systems all cover the geographic area by plurality of antennas and come work.It alignment is called the area radiation of cell in the present technique field.The AMPS cell is independently, thereby different with the cdma cellular district.This might make the cell antenna of a system be positioned at the cell of another system.Equally, in the specific system (AMPS, CDMA and TDMA), two ISPs are arranged in an appointed area.The normal selection of these ISPs places cell on the geographical position different with the competitor, and therefore, have such a case: the radio telephone of system ' A ' may be far away from the nearest cell of this system, and near from the cell of system ' B '.This situation means because multitone disturbs strong and signal weaker that will receive.

System antenna this mixes disturbs and may have problems to the mobile radiotelephone that is registered in the system (for example cdma system) and advance near the antenna (for example AMPS antenna) of another system.In this case, because radio telephone is higher near the power of AMPS cell or AMPS forward link signals, so the CDMA signal that the AMPS signal may disturb radio telephone receiving.

The multitone of the AMPS signal that radio telephone runs into disturbs and has produced distortion component.If these components drop in the CDMA frequency band of this radio telephone use, then they may reduce the performance of receiver and demodulator.

In the AMPS system, often communication common carrier (A and B frequency range) has disturbed competitor's system unintentionally.The purpose of cellular mobile operator is by making cell on-the-spot or near the user near communication, and the power that each AMPS channel radiation FCC is limited, and provides high s/n ratio to all users of its system.But unfortunately, this technology provides preferable signal quality for the system of communication common carrier, but its cost is the system that has disturbed the competitor.

The intermodulation distortion that causes such as above-mentioned situation defines with the peak value spurious level that the two or more tone signals that inject receiver produce.The most frequent is that receiver defines the third order distortion level with three rank input acquisition point or IIP3.IIP3 is defined as and produces the required input power (with the form of two tone signals) of third order distortion component that equals to import two tone signal power.As shown in figure 13, when when following, knowing IIP3 saturated linearly by inference such as non-linear components such as amplifiers.

As shown in figure 14, when two tone signals are injected into receiver, produce three sections distortion components.Tone signal #1 is on frequency f 1, and power level is P1 (dBm).Tone signal #2 is on frequency f 2, and power level is p2 (dBm).Generally P2 is arranged to equal P1.The third order distortion component is in frequency 2 * f1-f2 and the last generation of 2 * f2-f1, and power level is respectively P12 and P21.If P2 is arranged to equal P1, then parasitic component should equate, perhaps P12 and P21 should equate.Signal fc injects with power level Pc, is illustrated in this case, and the distortion of increase equals low level signal.If there is a filter to leach f1, f2 and f21 after producing distortion, the power of f12 will disturb the signal power at fc place.In the example of Figure 14, use for CDMA, its objective is gross power that intermode power P 12 should equal two tone signals signal power-105dBm for-43dBm, thus IIP3 necessary＞-9dBm.

In many institute's cycles in the present technique field, the IIP3 of-individual non-linear components is as giving a definition:

IIP3＝IM3/2＝Pin(dBm)

If P1=P2, then Pin=P1+3dB or P2+3dB (dBm), and

IM3＝P1-P12＝P2-P21＝P2-P12＝P1-P21(dB)

For the IIP3 of the cascade of having used a plurality of non-linear components, be formulated as follows:

Wherein, gain=to the gain of parts inputs.

Therefore, a kind of method of improving the IIP3 of receiver cascade is to reduce gain before first kind of non-linear components.In this case, LNA and frequency mixer have limited IIP3.Yet another is measured sensitivity or the minimum received signal level that not have interference is set to need definition.This amount is called noise factor (NF) in the present technique field.Improve IIP3 (and immunity to interference) if the gain of receiver is reduced to, then reduced NF (with to the little sensitivity that requires signal).

The NF of parts is defined as follows:

The NF=Si/Ni-So/No of parts (dB),

Wherein: Si/Ni is the input signal represented with the dB ratio to noise,

So/No is the output signal represented with the dB ratio to noise.

For the parts in the receiver cascade, this formula is as follows:

Wherein, NFe equals the noise factor of parts,

NFi equals the cascade noise coefficient to these parts,

Gain equals the operation gain to these parts.

If make the gain maximum of these parts, then can realize ' best ' cascade NF, the contradiction that requires of this formula and ' best ' cascade IIP3.For parts one by one, receiver NF and the IIP3 of appointment, there is limited gain sets in each parts, satisfies all requirements.

Usually, receiver is designed to NF and IIP3 is a predetermined constant, these two amounts are provided with receiver dynamic duty scope when noiseless.According to scale, cost, heat, static state and dynamic component current drain, make gain, NF and IIP3 the best of each device.In double mode CDMA/FM portable cellular shape mobile communication receiver, the CDMA standard-required has the NF of 9dB under minimum signal.In other words, for the CDMA pattern, it is to be the S/N ratio of 0dB under-104dBm that sensitivity requires.For the FM pattern, requirement is to be the S/N ratio of 4dB under-116dBm.In both cases, this requirement can convert the following requirement to NF to:

NF=S (dBm)-S/N (dB)-N _Therm(dBm/Hz)-signal BW (dB/Hz),

Wherein, S is a minimum signal power,

S/N is minimum signal to noise ratio,

N _ThermFor the thermal noise minimum (174dBm/Hz@290K),

Signal BW (dB/Hz) is the bandwidth of signal.

Therefore, the NF=-104dBm-0dB-of CDMA (174dBm/Hz)-61dB/Hz=9dB,

The NF=-116dBm-4dB-of FM (174dBm/Hz)-45dB/Hz=9dB,

Wherein-61dBm/Hz is the noise bandwidth of CDMA Channel,

-45dBm/Hz is the noise bandwidth of FM channel.

Yet just the NF to receiver has requirement when signal receives minimum levels, and just IIP3 is had requirement when having interference or strong CDMA signal.

Have only two kinds of approach to cover communication common carrier and producing strongly disturbing zone.A kind ofly be to use identical technology, even the position of cell and competitor's is the same.Another kind is an immunity to interference of improving receiver.A method improving immunity to interference is to improve the electric current of receiver.Yet this is not the available solution of a kind of reality, because portable wireless transmitting-receiving receiver relies on battery operated.Increase electric current and will make battery consumption faster, thereby reduced wireless telephonic conversation and stand-by time.So need make the multitone in the radio telephone disturb minimum and not influence power consumption.

Summary of the invention

The invention provides a kind of device that improves radio receiver radio frequency interference immunity to interference, comprise: be connected to first switch of the signal that receives, this switch has primary importance and the second place second place is connected on the bypass path; First amplifier is used to amplify the signal that receives, and its input is connected on the primary importance of first switch, and output is connected on the bypass path; Be connected to the controller of first switch, surpass predetermined power level in response to the signal that receives, switch transition on make position.

Method of the present invention comprises the following step: the power level that detects the radio signal that receives; If power level is equal to or greater than predetermined threshold, just reduce the gain of reception amplifier.

Summary of drawings

Fig. 1 shows the block diagram that the present invention improves the device of noise immunity of receiver.

Fig. 2 shows the block diagram of another embodiment of the present invention.

Fig. 3 shows the block diagram of another embodiment of the present invention.

Fig. 4 shows the block diagram of another embodiment of the present invention.

Fig. 5 shows according to the RF input power that receives of the embodiment of Fig. 7 another curve chart to carrier-to-noise ratio.

Fig. 6 shows according to the RF input power that receives of the embodiment of Fig. 8 curve chart to carrier-to-noise ratio.

Fig. 7 shows the block diagram of another embodiment of the present invention.

Fig. 8 shows and need not of the present inventionly install, and interference power is to the curve chart of signal power.

Fig. 9 shows according to another embodiment interference power of apparatus of the present invention curve chart to signal power.

Figure 10 shows the block diagram of another embodiment of the present invention.

Figure 11 shows the block diagram of another embodiment of the present invention.

Figure 12 shows the block diagram of another embodiment of the present invention.

Figure 13 shows the curve chart of non-linear transmission characteristic and distortion measurement.

Figure 14 shows the frequency spectrum of distortion component and describes.

Figure 15 shows the block diagram according to the method for detection received signal power of the present invention.

Figure 16 shows the flow chart of decay control method of the present invention.

Embodiments of the present invention

The NF and the IIP3 that the objective of the invention is to change in case of necessity receiver improve IIP3 (or immunity to interference), and do not influence NF.' raising ' of this performance is to realize by the gain that changes first dynamic component in the receiver.Gain that can be by in a continuous scope, changing LNA or disconnect low noise amplifier with by-pass switch and change.

Fig. 1 shows the block diagram of preferred embodiment of the present invention.

Present embodiment has comprised and utilizes adjustable gain control (AGC) 110 to regulate LNA115 continuously at the front end of receiver.The benefit that continuous AGC110 on the front end also provides is linear on the RF of minimum incoming level, and may reduce the requirement of IF AGC125 and 130 at the AGC120 of emitting side.

This embodiment detects the power output of LNA115.Power detector 105 is measured signal power and interference power on RF.Utilize present embodiment, power detector 105 can received power be lower than aftermentioned Fig. 7,10,11 and 12 " conversion gain " embodiment-during 65dBm, reduce the gain of LNA115 continuously.

This preferred embodiment detects signal and the interference power that receives by power detector 105 on RF.This detected power is used for regulating receiving AGC110 by loop filter, thereby regulates the capture point of receiving element.Reduce gain when recording when power increases, when the power that records reduces, improve gain.Present embodiment can also be formed formation gain-variable LNA to LNA115 and AGC110, does not therefore need independent AGC110 piece.Regulate the power that is arranged on the emission AGC120 before the power amplifier 150 with the method identical, to keep total transmitted power level with receiving AGC110.

AGC amplifier

125 and 130 also are set behind

frequency mixer

135 and 140, with in band pass filter 145 filterings regulate after disturbing and gain.These

AGC amplifiers

125 and 130 are realized the normal CDMA function of open Loop Power control, closed power control and compensation.Because the wide dynamic range of CDMA is so need these IFAGC125 and 130.Usually, these AGC125 and 130 gain ranging are greater than 80dB.Reception behind frequency mixer and emission AGC125 and 130 are regulated by the power detector of the gross power after another measurement received signal down-conversion.When the power of down-conversion signal increased, power detector 150 was regulated the gain of AGC125 and 130 downwards, and when the power of down-conversion signal reduces, the gain to adjusted AGC125 and 130.

In preferred embodiment, the signal that receives is in the frequency band of 869-894MHz.The signal of emission is in the frequency band of 824-849MHz.Another embodiment uses different frequencies.

Curve shown in Figure 5 shows the benefit of this AGC method.Left-hand side y axle shows the carrier-to-noise ratio of carrier noise comparison with respect to the parameterized reception input power of interference level.The y axle of right-hand side shows the required total interference power of constant C/J as the function that receives input power.(100dBm), wireless device resembles does not have to work the RF AGC when not existing when disturbing.When disturbing increase, C/N reduces, but effectively the linearity also increases.In this example, the RF dynamic range is 30dB, and the threshold value that RFAGC works is positioned on the point of interference power greater than-25dBm.

Fig. 2 shows another embodiment of continuous gain-adjusted.This embodiment is at first before power detector 210 is determined the power level of down-conversion signal, with band pass filter 205 filtering interfering.Threshold dector 225 determines that signal power levels reach certain and a bit (are-105dBm) time in the present embodiment, when signal power during above this power level, regulate the gain of AGC230 and 235 downwards then.When signal power level is lower than this threshold value, the gain to adjusted AGC230 and 235.Be adjusted in the AGC215 of

frequency mixer

240 and 245 front and back and 220 gain continuously, and do not check the predetermined threshold of power, carry out the AGC power control of normal CDMA.

Fig. 6 shows the curve chart of this embodiment.When threshold value is arranged on-during 105dBm (minimum receive RF level), C/N does not resemble quick increase the situation that does not have RF AGC.The advantage of present embodiment is when the RF input power is very low linear benefit just have been arranged, do not need to receive the RF power detector, and AGC loop detection signal power only.Therefore, the design of AGC loop is than detecting the simple of RF power.

Fig. 3 shows an alternative embodiment of the invention.The work of this embodiment is similar to the embodiment of Fig. 1.Unique difference is that AGC301 is placed into before the LNA305 that receives path.

Fig. 4 shows an alternative embodiment of the invention.This embodiment has used attenuator 405 between antenna 410 and duplexer 415.Power detector 420 controls of this attenuator after by LNA425.Power detector 420 is measured signal and the interference power that receives, and carries out filtering, and it and predetermined threshold value are compared.In the present embodiment, threshold value is-25dB.When the signal of combination and interference power when reaching this threshold value, improve the attenuation of attenuator 405.This adjusting can be carried out with digital fixed step size or continuous method.AGC430 behind

frequency mixer

440 and 445 regulates in the mode identical with the preferred embodiment of Fig. 1 with 435.

Fig. 7 shows another embodiment of device of the present invention.This embodiment has used

switch

701 and 702 to change front-end gain.For specific cdma wireless phone design, actual switching levels is relevant with the signal to noise ratio requirement as the function of signal level or noise factor.The present invention can be used for the AMPS radio telephone, yet will change transfer characteristic to adapt to different working points.

Present embodiment comprises the antenna 725 that receives and transmit.Reception and transmission path in the wireless device are connected on the antenna 725 by duplexer 720, and duplexer separates the signal that receives with transmitting.

The signal that receives is input on the LNA703, and LNA703 is connected between two switches 701 and 702.A switch 701 is connected to LNA703 on the duplexer 720, and second switch 702 is connected to LNA703 on the band pass filter 704.In preferred embodiment,

switch

701 and 702 is the single-pole double throw GaAs switch.

LNA703 is connected on the contact of each switch, and when two

switches

701 and 702 were transformed on these contacts, the signal that receives was connected to LNA703, and the amplifying signal of LNA703 is outputed to band pass filter 704.In the present embodiment, the frequency band of band pass filter 704 is 869-894MHz.Another embodiment uses the different frequency band of the signal frequency that depends on reception.

Be connected on another contact of each switch with road 730 all.When

switch

701 and 702 was transformed into their another contact, the received signal of duplexer 720 got around LNA703, directly guidance tape bandpass filter 704.In the present embodiment, these

switches

701 and 702 are subjected to the control of radio telephone microcontroller 740.In another embodiment, control the position of these switches with independent controller.

After band pass filter 704 has carried out filtering to the received signal, be down-converted to lower intermediate frequency (IF) through the signal of filtering, use for the remainder of wireless set.Down-conversion is to finish after mixing by 705 signals that receive of frequency mixer and another signal with frequency of phase-locked loop 707 drive pressure control generators 706 settings.Back one signal was amplified by amplifier 750 before being input to frequency mixer 705.

The down-conversion signal of frequency mixer 705 is input to rear end AGC708 and 709.These AGC708 and 709 are used to carry out closed power control by radio telephone, and this present technique field has been known.

In the method for the invention, microcontroller 740 monitors the power of the signal that receives.When power surpass-during 65dBm, microcontroller 740

command switchs

701 and 702 are transformed into bypass position, therefore a signal that receives directly are connected to band pass filter 704.By the gain of bypass LNA703, improve the capture point of receiver pro rata with the minimizing that with dB is the gain of unit.Another embodiment uses other circuit and the method power that monitors the signal that receives.

Another embodiment of the inventive method regulates the gain of front end continuously.Present embodiment uses the low-power threshold value such as-25dBm.

The curve chart of Fig. 8 and Fig. 9 shows the advantage of the convertible gain embodiment of the present invention shown in Fig. 7,10,11 and 12.Fig. 8 shows the curve chart of the interference power of the general wireless device that does not use convertible gain apparatus to radio frequency (RF) signal power.This curve representation, maximum interference level are limited in-10.On the receiver input compression point of 5dBm.There is shown the power curve of one and two tone signal.

The variation of the radiofrequency signal power that the interference power that the curve representation wireless device of Fig. 9 receives receives the wireless device that utilizes convertible gain method of the present invention and device.As can be seen, curve-the 65dBm point on, switch transition becomes bypass LNA gain, therefore can admit of bigger interference power and does not influence the RF signal power.There is shown the power curve of one and two tone signal.

Figure 10 show apparatus of the present invention another embodiment.This embodiment uses a single-pole single-throw switch (SPST) 1001.In this embodiment, when the signal power that receives reach-during 65dBm, controller 1020 is transformed into switch 1001 on the bypass path 1010.This effectively short circuit the LNA1002 gain, thereby, the signal that receives directly is connected on the band pass filter 1003.

Figure 11 shows another embodiment of apparatus of the present invention.This embodiment has used a single-pole single-throw switch (SPST) 1105, when it is closed, just LNA1110 is become ground connection by resistor 1101 short circuits.This causes impedance mismatching at input, causes signal attenuation, therefore, has reduced the gain of LNA1110.The same with the foregoing description, when input signal power reach-during 65dBm, switch 1105 closures.The resistance of resistor 1101 is relevant with desired attenuation.In another embodiment, this resistance is different for different LNA.

Figure 12 shows another embodiment of apparatus of the present invention.This embodiment has used a single-pole double-throw switch (SPDT) 1201 at the output of LNA1205.LNA1205 is connected on the contact of switch 1201, and bypass path 1210 is connected on another contact.The input of bypass path 1210 is connected to the input of LNA1205.When the power level of the RF signal that receives reach-during 65dBm, switch 1201 is thrown to bypass path 1210 from the position that LNA1205 is connected to band pass filter 1220.So just signal directly is connected to band pass filter 1220, bypass the gain of LNA1205.

Above among all embodiment, in by switch bypass, can close to LNA and power.This can also realize on the switch by this controller control by the power end of LNA being connected to one.In case LNA by bypass, does not re-use, with regard to powered-down.This has reduced the power consumption of wireless device, thereby improves operable conversation of battery and stand-by time.

In another embodiment of the present invention, Ec/Io detects the time that is used for determining to regulate front-end gain.Additional embodiments is used other quality yardstick, for example Eb/Io.

These are than the quality yardstick that is the digital communication system performance.Eb/Io is than the total interference spectrum density of the energy of representing every bit than channel, and the energy of the Ec/Io ratio every CDMA chip of expression (raising unit) is than total interference spectrum density.Can think that Eb/Io is a kind of tolerance, it has represented the characteristic of a communication system to another system; The Eb/Io that needs is more little, and system modulation and detection process are effective more to given error probability.Suppose to obtain easily Ic/Io and the signal strength signal intensity that receives, when Ec/Io descended, microcontroller just can detect strongly disturbing existence, and the interference that the AGC detector increases.Microcontroller can reduce front-end gain, and to improve immunity to interference, this will improve Ec/Io, reduces the interference components that drops in the signal bandwidth.

When signal quality reaches above-mentioned Eb/Io or Ec/Io threshold value, reduce front-end gain.Can utilize method for continuously adjusting or amplifier conversion method or above-mentioned these two kinds of methods to realize this gain-adjusted.

Another embodiment shown in Figure 15 will detect the signal power of IF or base band, rather than the combination of the signal of RF and interference power.This method is simpler, and it has only a power detector AGC control loop.

Figure 15 shows the block diagram of the another kind of method of the power that detects the signal that receives.At first 1501 this signal is down-converted to base band frequency.1505 become digital signal to this analog signal conversion then, to carry out further Base-Band Processing, comprising the intensity of the signal of determining to receive.Each chip energy that chip correlators 1510 is determined all irrelevant parts energy.Processor 1515 utilizes this information and received signal volume indicator (RSSI) to determine the gain adjustment amount of receiver 1520 and transmitter 1530.

Because the received signal power yardstick comprises signal and interference power, so only when the energy of signal level and every chip all descends, receiving gain just improves.Because RSSI changes,, compensating, thereby open Loop Power control can suitably be worked so transmitting power also must change.Therefore, when receiving gain was regulated, processor was just regulated transmitting gain.

Other embodiment uses removing or signal power to come the variable AGC of ride gain.Additional embodiments is only controlled received power rather than is transmitted and received power and all controls.

Figure 16 illustrates the method for the gain controlling of the foregoing description.This method is based on the relation shown in the curve chart of Figure 13.In Figure 13, can see that intermodulation component (following curve) is faster than interference power increase along with the increase of disturbing input power along X-axis.Therefore,, on input, apply the decay of XdB, can reduce 3 to the IM3 intermodulation component if occur disturbing at receiver inlet ^*XdB.

Usually, intermodulation component does not drop into the IF part of wireless device, and this is because their power is lower.The outer intermodulation component of IF part can not cause the receiver performance problem.Therefore, if intermodulation component has enough power influences IF signals, just must regulate the gain of receiver.

With reference to Figure 16, method of the present invention is at first regulated input gain (1601).In preferred embodiment, this gain-adjusted is 3dB.Yet other embodiment can use other gain-adjusted value, for example 1dB-6dB scope.Then, the processing of receiver is used to measure the variable power (1605) of the signal that receives.In preferred embodiment, the automatic gain control and treatment detects the IF signal power variations.The variation that should be appreciated that the signal that measurement receives also can be carried out in the RF of receiver level or base band level.

If signal power variations is near 3dB, then there is not the possibility of the intermodulation component that causes problem in the CDMA signal greater than noise floor.In this case, do not need to carry out other gain-adjusted, but improve the sensitivity that gain will improve receiver.The IF signal power variations is still regarded 3dB as near (3+-0.5) dB.

If the IF signal power variations is less than 3dB (1610), then the CDMA signal does not perhaps have the intermodulation component that may cause problem less than noise floor.In this case, AGC only sees little CDMA signal and noise.Therefore, must improve the gain (1615) of receiving circuit, thus the sensitivity that improves receiver.

If the IF signal power variations is greater than 3dB, then intermodulation component is enough to have problems, and must carry out other gain-adjusted 1620.In preferred embodiment, if input gain changes 3dB, when occurring when disturbing, intermodulation component will change 9dB.In this case, (for example 3dB) reduces average gain slightly, until method of the present invention determines that intermodulation component is reduced to acceptable degree.

Method of the present invention can be used for low rate ground continuous review intermodulation component.In preferred embodiment, this speed is per second 10 times.Other embodiment uses each frame period method once.Other embodiment uses other speed, just checks when for example detecting bigger mistake on forward link.

In a word, method of the present invention can make vehicular radio advance to antenna near different system, and the resistivity of wireless device to the radio frequency interference of another system is provided simultaneously.By reducing front-end gain, the capture point of radio receiver circuit increases, and the distortion component that the signal of other system is caused can not cause receiver and demodulator performance to reduce.

Claims

1, a kind of device that improves radio receiver radio frequency interference immunity to interference, this receiver is characterized in that in received signal described device comprises:

Be connected to first switch of the signal that receives, this switch has primary importance and the second place second place is connected on the bypass path;

First amplifier is used to amplify the signal that receives, and its input is connected on the primary importance of first switch, and output is connected on the bypass path;

Be connected to the controller of first switch, surpass predetermined power level in response to the signal that receives, switch transition on make position.

2, the device of raising radio receiver radio frequency interference immunity to interference as claimed in claim 1 is characterized in that, also comprises: second switch, have the primary importance and the second place, and primary importance is connected to first amplifier, and the second place is connected to bypass path;

Described controller also is connected on the second switch, and controller surpasses predetermined power level in response to the signal that receives, and first switch and second switch are transformed on the second place.

3, the device of raising radio receiver radio frequency interference immunity to interference as claimed in claim 1 is characterized in that predetermined power level is-65dBm.

4, the device of raising radio receiver radio frequency interference immunity to interference as claimed in claim 1 is characterized in that, amplifier is a low noise amplifier.

5, the device of raising radio receiver radio frequency interference immunity to interference as claimed in claim 1 is characterized in that, also comprises:

Be connected to the filter on first amplifier out, output is through the received signal of filtering on the filter output of filter;

Oscillator is used to produce the oscillator signal of preset frequency;

Have the frequency mixer of the first input end and second input, first input end is connected to the output of filter, and second input is connected to oscillator, and mixer response produces down-conversion signal in oscillator signal with through the received signal of filtering;

Second amplifier that connects down-conversion signal;

The 3rd amplifier that connects down-conversion signal;

Be connected to the first surface acoustic wave filter on second amplifier, be used to produce the signal that uses in the digital telephone system.

6, the device of raising radio receiver radio frequency interference immunity to interference as claimed in claim 1 is characterized in that described device also comprises:

Resistance, first end of resistance is connected to the primary importance of first switch, and second end of resistance is connected on the earthing potential.

7, a kind of device that improves radio receiver radio frequency interference immunity to interference, this receiver has received signal, it is characterized in that, and described device comprises:

Amplifier, the signal that its input receives is used for producing the received signal of amplifying at output;

Be connected to the bypass path of amplifier in;

Switch with primary importance and second place, primary importance are connected to the output of amplifier, and the second place is connected on the bypass path;

Be connected to the controller on the switch, surpass predetermined power level in response to the signal that receives, switch transition on the second place.

8, a kind of method that improves radio receiver radio frequency interference immunity to interference, radio receiver has reception amplifier and receives the electric wire signal of telecommunication, it is characterized in that, and described method comprises the following step:

The power level of the radio signal that detection receives;

If power level is equal to or greater than predetermined threshold, just reduce the gain of reception amplifier.

9, method as claimed in claim 8 is characterized in that, the step that reduces the reception amplifier gain comprises the bypass reception amplifier.

10, method as claimed in claim 8 is characterized in that, the step that reduces reception amplifier gain is included between the radio signal that receives and the reception amplifier and produces impedance mismatching.